Coating architecture for plasma sprayed chamber components

ABSTRACT

A method of plasma spraying an article comprises providing an article, feeding a liquid precursor solution into a plasma spray deposition system, and generating, with the plasma spray deposition system, a stream directed toward the article. The stream forms a ceramic coating on the article upon contact therewith. The ceramic coating comprises Y2O3 and one or more of ZrO2, Al2O3, Er2O3, Gd2O3, SiO2, or YF3.

RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 15/640,274, filed Jun. 30, 2017, which is a divisionalapplication of U.S. patent application Ser. No. 14/462,057, filed Aug.18, 2014, which claims the benefit under 35 U.S.C. § 119(e) of U.S.Provisional Application No. 61/879,549, filed Sep. 18, 2013, each ofwhich is incorporated by reference herein in their entireties.

TECHNICAL FIELD

Embodiments of the present disclosure relate, in general, to ceramiccoated articles and to a process for plasma spraying a ceramic coatingonto chamber components.

BACKGROUND

In the semiconductor industry, devices are fabricated by a number ofmanufacturing processes producing structures of an ever-decreasing size.Some manufacturing processes such as plasma etch and plasma cleanprocesses expose a substrate to a high-speed stream of plasma to etch orclean the substrate. The plasma may be highly corrosive, and may corrodeprocessing chambers and other surfaces that are exposed to the plasma.This corrosion may generate particles, which frequently contaminate thesubstrate that is being processed, contributing to device defects.

As device geometries shrink, susceptibility to defects increases, andparticle contaminant requirements become more stringent. Accordingly, asdevice geometries shrink, allowable levels of particle contamination maybe reduced. To minimize particle contamination introduced by plasma etchand/or plasma clean processes, chamber materials have been developedthat are resistant to plasmas. Different materials provide differentmaterial properties, such as plasma resistance, rigidity, flexuralstrength, thermal shock resistance, and so on. Also, different materialshave different material costs. Accordingly, some materials have superiorplasma resistance, other materials have lower costs, and still othermaterials have superior flexural strength and/or thermal shockresistance.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings in which likereferences indicate similar elements. It should be noted that differentreferences to “an” or “one” embodiment in this disclosure are notnecessarily to the same embodiment, and such references mean at leastone.

FIG. 1 depicts a sectional view of one embodiment of a processingchamber.

FIG. 2 illustrates an exemplary architecture of a manufacturing system,in accordance with one embodiment of the present invention.

FIG. 3 depicts a schematic of a plasma spray deposition system.

FIG. 4 depicts a further schematic of a plasma spray deposition system.

FIG. 5 illustrates one embodiment of a process for forming multipleplasma sprayed ceramic coating over a chamber component.

FIG. 6 illustrates a cross sectional side view of articles covered byone or more plasma sprayed protective layers.

FIG. 7 illustrates a further cross sectional side view of articlescovered by one or more plasma sprayed protective layers.

DETAILED DESCRIPTION OF EMBODIMENTS

Some embodiments of the disclosure are directed to a process for forminga plasma resistant ceramic coating having a stack of at least twoprotective layers on an article. The at least two protective layers mayhave different thicknesses and/or densities and are deposited usingdifferent plasma spray processes. The processes disclosed herein provideimproved plasma resistance performance for chamber components.

In one embodiment, an article (e.g., a chamber component) is insertedinto a low pressure plasma spray chamber. A low pressure plasma sprayprocess is performed by a plasma spraying system to form a first plasmaresistant layer having a thickness of 100-200 microns and a porosity ofover 1%. The plasma spraying system then performs a plasma spray thinfilm (PSTF), plasma spray physical vapor deposition (PSPVD) or plasmaspray chemical vapor deposition (PSCVD) process to deposit a secondplasma resistant layer on the first plasma resistant layer, the secondplasma resistant layer having a thickness of 1-50 microns and a porosityof less than 1%. The PSTF, PSCVD or PSPVD plasma spray process may beperformed by the same low pressure plasma spray chamber that performsthe low pressure plasma spray process. Additionally, the PSTF, PSCVD orPSPVD plasma spray process may be performed immediately after the lowpressure plasma spray process as part of a single deposition recipe.Alternatively, the first plasma spray process may be an atmosphericpressure plasma spray (APPS) process (also referred to as an air plasmaspray (APS) process. In such an embodiment, the article would be placedinto a low pressure plasma spray chamber to perform the PSTF, PSCVD orPSPVD process after performing the APPS process.

The ceramic coating of the article may be highly resistant to plasmaetching, and the article may have superior mechanical properties such asa high flexural strength and a high thermal shock resistance.Performance properties of the coated ceramic article may include a highthermal capability, a long lifespan, and a low on-wafer particle andmetal contamination. Additionally, by performing both the low pressureplasma spray process and the PSTF, PSCVD or PSPVD plasma spray processesin the same low pressure plasma spray chamber, cycle time and cost maybe reduced.

When the terms “about” and “approximately” are used herein, these areintended to mean that the nominal value presented is precise within±30%. The articles described herein may be structures that are exposedto plasma, such as chamber components for a plasma etcher (also known asa plasma etch reactor). For example, the articles may be walls, bases,gas distribution plates, rings, view ports, lids, nozzles, shower heads,substrate holding frames, electrostatic chucks (ESCs), face plates,selectivity modulation devices (SMDs), etc. of a plasma etcher, a plasmacleaner, a plasma propulsion system, and so forth.

Moreover, embodiments are described herein with reference to ceramiccoated chamber components and other articles that may cause reducedparticle contamination when used in a process chamber for plasma richprocesses. However, it should be understood that the ceramic coatedarticles discussed herein may also provide reduced particlecontamination when used in process chambers for other processes such asnon-plasma etchers, non-plasma cleaners, chemical vapor deposition (CVD)chambers, physical vapor deposition (PVD) chambers, and so forth.Moreover, some embodiments are described with reference to specificplasma resistant ceramics. However, it should be understood thatembodiments equally apply to other plasma resistant ceramics than thosediscussed herein.

FIG. 1 is a sectional view of a processing chamber 100 (e.g., asemiconductor processing chamber) having one or more chamber componentsthat are coated with a ceramic coating in accordance with embodiments ofthe present invention. The processing chamber 100 may be used forprocesses in which a corrosive plasma environment is provided. Forexample, the processing chamber 100 may be a chamber for a plasma etchreactor (also known as a plasma etcher), a plasma cleaner, and so forth.Examples of chamber components that may include a plasma resistantceramic coating include a substrate support assembly 148, anelectrostatic chuck (ESC) 150, a ring (e.g., a process kit ring orsingle ring), a chamber wall, a base, a gas distribution plate, ashowerhead, a liner, a liner kit, a shield, a plasma screen, a flowequalizer, a cooling base, a chamber viewport, a chamber lid, a nozzle,process kit rings, and so on.

In one embodiment, the plasma resistant ceramic coating, which isdescribed in greater detail below, is a multi-layer rare earth oxidecoating deposited by a combination of a low pressure plasma spraying(LPPS) process and one of a plasma spray thin film (PSTF) process, aplasma spray chemical vapor deposition (PSCVD) process or a plasma sprayphysical vapor deposition (PSPVD) process. Alternatively, the plasmaresistant ceramic coating may be a multi-layer rare earth oxide coatingdeposited by a combination of an atmospheric pressure plasma spray(APPS) process and one of a PSTF, PSCVD or PSPVD process.

The plasma resistant ceramic coating may have multiple plasma resistantlayers, in accordance with embodiments. The multiple layers may eachhave the same material composition or may have different materialcompositions. Any of the layers of the plasma resistant coating mayinclude Y₂O₃ and Y₂O₃ based ceramics, Y₃Al₅O₁₂ (YAG), Al₂O₃ (alumina),Y₄Al₂O₉ (YAM), SiC (silicon carbide) Si₃N₄ (silicon nitride), SiN(silicon nitride), MN (aluminum nitride), TiO₂ (titania), ZrO₂(zirconia), TiC (titanium carbide), ZrC (zirconium carbide), TiN(titanium nitride), Y₂O₃ stabilized ZrO₂ (YSZ), Er₂O₃ and Er₂O₃ basedceramics, Gd₂O₃ and Gd₂O₃ based ceramics, Er₃Al₅O₁₂ (EAG), Gd₃Al₅O₁₂(GAG), Nd₂O₃ and Nd₂O₃ based ceramics, and/or a ceramic compoundcomprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂.

Any of the layers of the plasma resistant ceramic coating may also bebased on a solid solution formed by any of the aforementioned ceramics.With reference to the ceramic compound comprising Y₄Al₂O₉ and asolid-solution of Y₂O₃—ZrO₂, in one embodiment the ceramic compoundincludes 62.93 molar ratio (mol %) Y₂O₃, 23.23 mol % ZrO₂ and 13.94 mol% Al₂O₃. In another embodiment, the ceramic compound can include Y₂O₃ ina range of 50-75 mol %, ZrO₂ in a range of 10-30 mol % and Al₂O₃ in arange of 10-30 mol %. In another embodiment, the ceramic compound caninclude Y₂O₃ in a range of 40-100 mol %, ZrO₂ in a range of 0-60 mol %and Al₂O₃ in a range of 0-10 mol %. In another embodiment, the ceramiccompound can include Y₂O₃ in a range of 40-60 mol %, ZrO₂ in a range of30-50 mol % and Al₂O₃ in a range of 10-20 mol %. In another embodiment,the ceramic compound can include Y₂O₃ in a range of 40-50 mol %, ZrO₂ ina range of 20-40 mol % and Al₂O₃ in a range of 20-40 mol %. In anotherembodiment, the ceramic compound can include Y₂O₃ in a range of 70-90mol %, ZrO₂ in a range of 0-20 mol % and Al₂O₃ in a range of 10-20 mol%. In another embodiment, the ceramic compound can include Y₂O₃ in arange of 60-80 mol %, ZrO₂ in a range of 0-10 mol % and Al₂O₃ in a rangeof 20-40 mol %. In another embodiment, the ceramic compound can includeY₂O₃ in a range of 40-60 mol %, ZrO₂ in a range of 0-20 mol % and Al₂O₃in a range of 30-40 mol %. In other embodiments, other distributions mayalso be used for the ceramic compound.

In one embodiment, an alternative ceramic compound that includes acombination of Y₂O₃, ZrO₂, Er₂O₃, Gd₂O₃ and SiO₂ is used for one or morelayers of the plasma resistant ceramic coating. In one embodiment, thealternative ceramic compound can include Y₂O₃ in a range of 40-45 mol %,ZrO₂ in a range of 0-10 mol %, Er2O3 in a range of 35-40 mol %, Gd₂O₃ ina range of 5-10 mol % and SiO2 in a range of 5-15 mol %. In a firstexample, the alternative ceramic compound includes 40 mol % Y₂O₃, 5 mol% ZrO₂, 35 mol % Er₂O₃, 5 mol % Gd₂O₃ and 15 mol % SiO₂. In a secondexample, the alternative ceramic compound includes 45 mol % Y₂O₃, 5 mol% ZrO₂, 35 mol % Er₂O₃, 10 mol % Gd₂O₃ and 5 mol % SiO₂. In a thirdexample, the alternative ceramic compound includes 40 mol % Y₂O₃, 5 mol% ZrO₂, 40 mol % Er₂O₃, 7 mol % Gd₂O₃ and 8 mol % SiO₂.

Any of the aforementioned plasma resistant ceramic coatings may includetrace amounts of other materials such as ZrO₂, Al₂O₃, SiO₂, B₂O₃, Er₂O₃,Nd₂O₃, Nb₂O₅, CeO₂, Sm₂O₃, Yb₂O₃, or other oxides. The ceramic coatingallows for longer working lifetimes due to the plasma resistance of theceramic coating and decreased on-wafer or substrate contamination.Beneficially, in some embodiments the ceramic coating may be strippedand re-coated without affecting the dimensions of the substrates thatare coated.

In one embodiment, the processing chamber 100 includes a chamber body102 and a lid 130 that enclose an interior volume 106. The lid 130 mayhave a hole in its center, and a nozzle 132 may be inserted into thehole. The chamber body 102 may be fabricated from aluminum, stainlesssteel or other suitable material. The chamber body 102 generallyincludes sidewalls 108 and a bottom 110. Sidewalls 108 and/or bottom 110may include a plasma resistant ceramic coating.

An outer liner 116 may be disposed adjacent the sidewalls 108 to protectthe chamber body 102. The outer liner 116 may be fabricated and/orcoated with a plasma resistant ceramic coating. In one embodiment, theouter liner 116 is fabricated from aluminum oxide.

An exhaust port 126 may be defined in the chamber body 102, and maycouple the interior volume 106 to a pump system 128. The pump system 128may include one or more pumps and throttle valves utilized to evacuateand regulate the pressure of the interior volume 106 of the processingchamber 100.

The lid 130 may be supported on the sidewall 108 of the chamber body102. The lid 130 may be opened to allow access to the interior volume106 of the processing chamber 100, and may provide a seal for theprocessing chamber 100 while closed. A gas panel 158 may be coupled tothe processing chamber 100 to provide process and/or cleaning gases tothe interior volume 106 through the nozzle 132. The lid 130 may be aceramic such as Al₂O₃, Y₂O₃, YAG, SiO₂, AlN, SiN, SiC, Si—SiC, or aceramic compound comprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂.The nozzle 132 may also be a ceramic, such as any of those ceramicsmentioned for the lid. The lid 130 may include a plasma resistantceramic coating 133. The nozzle 132 may be coated with a plasmaresistant ceramic coating 134.

Examples of processing gases that may be used to process substrates inthe processing chamber 100 include halogen-containing gases, such asC₂F₆, SF₆, SiCl₄, HBr, NF₃, CF₄, CHF₃, CH₂F₃, F, NF₃, Cl₂, CCl₄, BCl₃and SiF₄, among others, and other gases such as O₂, or N₂O. Examples ofcarrier gases include N₂, He, Ar, and other gases inert to process gases(e.g., non-reactive gases). A substrate support assembly 148 is disposedin the interior volume 106 of the processing chamber 100 below the lid130. The substrate support assembly 148 holds a substrate 144 duringprocessing. A ring 146 (e.g., a single ring) may cover a portion of theelectrostatic chuck 150, and may protect the covered portion fromexposure to plasma during processing. The ring 146 may be silicon orquartz in one embodiment. The ring 146 may include a plasma resistantceramic coating.

An inner liner 118 may be coated on the periphery of the substratesupport assembly 148. The inner liner 118 may be a halogen-containinggas resist material such as those discussed with reference to the outerliner 116. In one embodiment, the inner liner 118 may be fabricated fromthe same materials of the outer liner 116. Additionally, the inner liner118 may be coated with a plasma resistant ceramic coating.

In one embodiment, the substrate support assembly 148 includes amounting plate 162 supporting a pedestal 152, and an electrostatic chuck150. The electrostatic chuck 150 further includes a thermally conductivebase 164 and an electrostatic puck 166 bonded to the thermallyconductive base by a bond 138, which may be a silicone bond in oneembodiment. The mounting plate 162 is coupled to the bottom 110 of thechamber body 102 and includes passages for routing utilities (e.g.,fluids, power lines, sensor leads, etc.) to the thermally conductivebase 164 and the electrostatic puck 166.

The electrostatic puck 166 may include a plasma resistant ceramiccoating. The thermally conductive base 164 and/or electrostatic puck 166may include one or more optional embedded heating elements 176, embeddedthermal isolators 174 and/or conduits 168, 170 to control a lateraltemperature profile of the substrate support assembly 148. The conduits168, 170 may be fluidly coupled to a fluid source 172 that circulates atemperature regulating fluid through the conduits 168, 170. The embeddedisolators 174 may be disposed between the conduits 168, 170 in oneembodiment. The optional embedded heating elements 176 is regulated by aheater power source 178. The conduits 168, 170 and optional embeddedheating elements 176 may be utilized to control the temperature of thethermally conductive base 164, thereby heating and/or cooling theelectrostatic puck 166 and a substrate (e.g., a wafer) 144 beingprocessed. The temperature of the electrostatic puck 166 and thethermally conductive base 164 may be monitored using a plurality oftemperature sensors 190, 192, which may be monitored using a controller195.

The electrostatic puck 166 may further include multiple gas passagessuch as grooves, mesas and other surface features that may be formed inan upper surface of the electrostatic puck 166. The gas passages may befluidly coupled to a source of a heat transfer (or backside) gas such asHe via holes drilled in the electrostatic puck 166. In operation, thebackside gas may be provided at controlled pressure into the gaspassages to enhance the heat transfer between the electrostatic puck 166and the substrate 144.

The electrostatic puck 166 includes at least one clamping electrode 180controlled by a chucking power source 182. The at least one clampingelectrode 180 (or other electrode disposed in the electrostatic puck 166or thermally conductive base 164) may further be coupled to one or moreRF power sources 184, 186 through a matching circuit 188 for maintaininga plasma formed from process and/or other gases within the processingchamber 100. The one or more RF power sources 184, 186 are generallycapable of producing RF signal having a frequency from about 50 kHz toabout 3 GHz and a power of up to about 10,000 Watts.

FIG. 2 illustrates an exemplary architecture of a manufacturing system200. The manufacturing system 200 may be a ceramics manufacturingsystem. In one embodiment, the manufacturing system 200 includesmanufacturing machines 201 (e.g., processing equipment) connected to anequipment automation layer 215. The manufacturing machines 201 mayinclude a bead blaster 202, one or more wet cleaners 203, and/or aplasma spraying system 204. The manufacturing system 200 may furtherinclude one or more computing device 220 connected to the equipmentautomation layer 215. In alternative embodiments, the manufacturingsystem 200 may include more or fewer components. For example, themanufacturing system 200 may include manually operated (e.g., off-line)manufacturing machines 201 without the equipment automation layer 215 orthe computing device 220.

Bead blaster 202 is a machine configured to roughen the surface ofarticles such as articles. Bead blaster 202 may be a bead blastingcabinet, a hand held bead blaster, or other type of bead blaster. Beadblaster 202 may roughen a substrate by bombarding the substrate withbeads or particles. In one embodiment, bead blaster 202 fires ceramicbeads or particles at the substrate. The roughness achieved by the beadblaster 202 may be based on a force used to fire the beads, beadmaterials, bead sizes, distance of the bead blaster from the substrate,processing duration, and so forth. In one embodiment, the bead blasteruses a range of bead sizes to roughen the ceramic article.

In alternative embodiments, other types of surface rougheners than abead blaster 202 may be used. For example, a motorized abrasive pad maybe used to roughen the surface of ceramic substrates. A sander mayrotate or vibrate the abrasive pad while the abrasive pad is pressedagainst a surface of the article. A roughness achieved by the abrasivepad may depend on an applied pressure, on a vibration or rotation rateand/or on a roughness of the abrasive pad.

Wet cleaners 203 are cleaning apparatuses that clean articles (e.g.,articles) using a wet clean process. Wet cleaners 203 include wet bathsfilled with liquids, in which the substrate is immersed to clean thesubstrate. Wet cleaners 203 may agitate the wet bath using ultrasonicwaves during cleaning to improve a cleaning efficacy. This is referredto herein as sonicating the wet bath.

In other embodiments, alternative types of cleaners such as dry cleanersmay be used to clean the articles. Dry cleaners may clean articles byapplying heat, by applying gas, by applying plasma, and so forth.

Plasma spraying system 204 is a machine configured to plasma spray aceramic coating to the surface of a substrate. Plasma spraying systemsare discussed in greater detail with reference to FIGS. 3-4.

The equipment automation layer 215 may interconnect some or all of themanufacturing machines 201 with computing devices 220, with othermanufacturing machines, with metrology tools and/or other devices. Theequipment automation layer 215 may include a network (e.g., a locationarea network (LAN)), routers, gateways, servers, data stores, and so on.Manufacturing machines 201 may connect to the equipment automation layer215 via a SEMI Equipment Communications Standard/Generic Equipment Model(SECS/GEM) interface, via an Ethernet interface, and/or via otherinterfaces. In one embodiment, the equipment automation layer 215enables process data (e.g., data collected by manufacturing machines 201during a process run) to be stored in a data store (not shown). In analternative embodiment, the computing device 220 connects directly toone or more of the manufacturing machines 201.

In one embodiment, some or all manufacturing machines 201 include aprogrammable controller that can load, store and execute processrecipes. The programmable controller may control temperature settings,gas and/or vacuum settings, time settings, etc. of manufacturingmachines 201. The programmable controller may include a main memory(e.g., read-only memory (ROM), flash memory, dynamic random accessmemory (DRAM), static random access memory (SRAM), etc.), and/or asecondary memory (e.g., a data storage device such as a disk drive). Themain memory and/or secondary memory may store instructions forperforming heat treatment processes described herein.

The programmable controller may also include a processing device coupledto the main memory and/or secondary memory (e.g., via a bus) to executethe instructions. The processing device may be a general-purposeprocessing device such as a microprocessor, central processing unit, orthe like. The processing device may also be a special-purpose processingdevice such as an application specific integrated circuit (ASIC), afield programmable gate array (FPGA), a digital signal processor (DSP),network processor, or the like. In one embodiment, programmablecontroller is a programmable logic controller (PLC).

In one embodiment, the manufacturing machines 201 are programmed toexecute recipes that will cause the manufacturing machines to roughen asubstrate, clean a substrate and/or article, coat a article and/ormachine (e.g., grind or polish) a article. In one embodiment, themanufacturing machines 201 are programmed to execute recipes thatperform operations of a multi-step process for manufacturing a ceramiccoated article, as described with reference to FIG. 5. The computingdevice 220 may store one or more ceramic coating recipes 225 that can bedownloaded to the manufacturing machines 201 to cause the manufacturingmachines 201 to manufacture ceramic coated articles in accordance withembodiments of the present disclosure.

FIGS. 3-4 illustrate an LPPS system 300 for plasma spraying amulti-layer plasma resistant ceramic coating on a chamber component orother article used in a corrosive system. The LPPS system 300 is aplasma spray system that includes a vacuum chamber 301 that can bepumped down to reduced pressure (e.g., to a vacuum of 1 Mbar, 10 Mbar,35 Mbar, etc.). The LPPS system 300 may perform LPPS processes, PSPVDprocesses, PSCVD processes and/or PSTF processes.

In one embodiment (as illustrated), the LPPS system 300 is used todeposit a porous, low density first protective layer 312 and a thinnerdense second protective layer 313 over the first protective layer 312.In an alternative embodiment, a conventional atmospheric pressure plasmaspray (APPS) system that operates at atmospheric pressure is used todeposit the porous, low density first protective layer 312, and the LPPS300 is used to deposit the thinner dense second protective layer 313over the first protective layer 312. An APPS system does not include anyvacuum chamber, and may instead include an open chamber or room.

In a plasma spray system, an arc is formed between two electrodesthrough which a gas is flowing. Examples of gas suitable for use in thelow pressure plasma spray system 300 include, but are not limited to,Argon/Hydrogen or Argon/Helium. As the gas is heated by the arc, the gasexpands and is accelerated through a shaped nozzle of a plasma torch304, creating a high velocity plasma jet 302.

FIG. 3 shows deposition of the first protective layer 312 by the LPPSsystem 300 using an LPPS process. Powder 309 composed of a ceramicand/or metal material is injected into the plasma jet 302 by a powderdelivery system 308. An intense temperature of the plasma jet 302 meltsthe powder 309 and propels the molten ceramic and/or metal materialtowards an article 310. Upon impacting with the article 310, the moltenpowder flattens, rapidly solidifies, and forms a first protective layer312 of a ceramic coating. The molten powder adheres to the article 310.The parameters that affect the thickness, density, and roughness of thefirst protective layer 312 of the ceramic coating include type ofpowder, powder size distribution, powder feed rate, plasma gascomposition, gas flow rate, energy input, pressure, and torch offsetdistance. In one embodiment, the LPPS system 300 performs an LPPSprocess to form the first protective layer 312 having a thickness of upto 50 microns. In another embodiment, the first protective layer 312formed by the LPPS process has a thickness of up to 500 microns.

For LPPS processes, a chamber pressure of around 20-200 mbar may be usedto produce coatings on the order of 20-500 microns. LPPS typically has ahigh velocity plasma jet flow. For LPPS, thermal energy of the plasmagas is converted to kinetic energy by the expansion of volume in the lowpressure environment. LPPS processes may produce ceramic coatings with aporosity of about 1-5%. For LPPS, metallurgical bonding or diffusionbonding is a dominant bonding mechanism.

In one embodiment, the first protective layer 312 is formed by an APPSsystem performing an APPS process. In one embodiment, the firstprotective layer 312 formed ty the APPS process has a thickness ofapproximately 20-500 microns. Alternatively, the first protective layer312 may have other thicknesses. An APPS process may produce ceramiccoatings having thicknesses of around 20 microns to several millimeters.The APPS process produces an oxide ceramic coating having a relativelyhigh porosity. For example, APPS processes may produce ceramic coatingswith a porosity of 1-5% in some embodiments. In some embodiments, APPSmay produce ceramic coatings with a porosity of up to about 10%. ForAPPS, the ceramic coating bonds to the substrate mainly by mechanicalbonding. As compared to LPPS, APPS typically has a lower velocity plasmajet flow with a higher temperature.

FIG. 4 shows deposition of the second protective layer 313 by the LPPSsystem 300 using one of a PSPVD, PSTF or PSCVD process. Feedstock 320composed of a ceramic and/or metal material is injected into the plasmajet 302 by a feedstock delivery system 315. For PSPVD and PSTFprocesses, the feedstock is a powder composed of a ceramic and/or metalmaterial. Accordingly, if a PSPVD process or PSTF process are to beperformed, then feedstock 320 may correspond to powder 309 and feedstockdelivery system 315 may correspond to powder delivery system 308.Moreover, if the second protective layer 313 is to have the samematerial composition of the first protective layer 312, then the samepowder 309 may be used to perform both the first protective layer 312and the second protective layer 313. For PSCVD processes, the feedstockis a liquid or vapor. Accordingly, if a PSCVD process is to beperformed, then a different feedstock is used for the second protectivelayer 313 and the first protective layer 312, even if the two protectivelayers are to have the same material composition.

For PSCVD, PSTF and PSPVD processes, an intense temperature of theplasma jet 302 melts or vaporizes the feedstock 320 and propels themolten or vapor ceramic and/or metal material towards article 310. Uponimpacting with the first protective layer 312, the molten powderflattens, rapidly solidifies, and forms a first protective layer 312 ofa ceramic coating. Alternatively, upon impacting the first protectivelayer 312 the vaporized powder changes phase to a solid and forms thesecond protective layer 313 of the ceramic coating. The molten orvaporized powder adheres to the first protective layer 312. Theparameters that affect the thickness, density, and roughness of thesecond protective layer 313 of the ceramic coating include type offeedstock, powder size distribution (if the feedstock is a powder), afeed rate, plasma gas composition, gas flow rate for the plasma, energyinput, pressure, and torch offset distance.

In one embodiment, the LPPS system 300 performs a PSPVD process to formthe second protective layer 313 having a thickness of 10-100 microns.PSPVD refers to a plasma spray process in which powder feedstock istypically vaporized and deposition occurs primarily from the vaporphase. Alternatively, PSPVD may melt powder feedstock to produce liquidsplats that build up to form the second protective layer 313. For PSPVDprocesses, a chamber pressure of around 0.1-50 mbar may be used toproduce dense coatings using high gun enthalpy to vaporize or meltceramic feedstock material. The ceramic coatings produced by PSPVD havea uniform thickness.

In one embodiment, the LPPS system 300 performs a PSTF process to formthe second protective layer 313 having a thickness of 10-100 microns.PSTF refers to a process with powder feedstock where deposition ispredominantly by molten droplets, similar to conventional plasma spraybut at greatly reduced chamber pressures. For PSTF processes, a pressureof around 0.1-50 mbar may be used to produce thin dense coatings fromliquid splats using a classical thermal spray approach but at highvelocity and enthalpy. PSTF processes are performed by sprayingparticles at high velocities (e.g., 400-800 meters per second (m/s) andhigh enthalpy (e.g., 8000-15,000 kJ/kg). The ceramic coatings producedby PSTF have a uniform thickness with minimal internal stresses.

In one embodiment, the LPPS system 300 performs a PSCVD process to formthe second protective layer 313 having a thickness of approximately 1 to50 microns. PSCVD refers to a plasma spray process in which an extremelylow pressure of less than 1 mbar (e.g., around 0.3-1.0 mbar) and arelatively low power of less than 10 kW are used to produce thin densecoatings having a thickness of less than 50 microns. The feedstock forPSCVD processes is liquid or gaseous precursors. The ceramic coatingsproduced by PSCVD have a uniform thickness.

FIG. 5 illustrates one embodiment of a process for forming multipleplasma sprayed protective layers over a chamber component. At block 502,an LPPS or APPS process is selected for plasma spraying a first plasmaresistant layer. At block 504, an article (e.g., a substrate) isprepared for coating. The article may be a metal substrate such asaluminum, copper, magnesium, or another metal or a metal alloy. Thearticle may also be a ceramic substrate, such as alumina, yttria, oranother ceramic or a mixture of ceramics. Preparing the article mayinclude shaping the article to a desired form, grinding, blasting orpolishing the article to provide a particular surface roughness and/orcleaning the article. In one embodiment, the article is roughened. Inanother embodiment, the article is not roughened prior to depositing theceramic coating.

At block 506, an article is placed into an APPS system or into a vacuumchamber of an LPPS system depending on an outcome at block 502. At block508, optimal powder characteristics for plasma spraying a ceramiccoating using an LPPS or APPS process are selected. In one embodiment,an optimized agglomerate powder size distribution is selected where 10%of agglomerate powder (D10) has a size of less than 10 μm, 50% ofagglomerate powder (D50) has a size of 20-30 μm and 90% of agglomeratepowder (D90) has a size of less than 55 μm.

Raw ceramic powders having specified compositions, purity and particlesizes are selected. The ceramic powder may be formed of any of the rareearth oxides previously discussed. The raw ceramic powders are thenmixed. These raw ceramic powders may have a purity of 99.9% or greaterin one embodiment. The raw ceramic powders may be mixed using, forexample, ball milling. The raw ceramic powders may have a powder size ina range of between about 100 nm-20 μm. In one embodiment, the rawceramic powders have a powder size of approximately 5 μm.

After the ceramic powders are mixed, they may be calcinated at aspecified calcination time and temperature. In one embodiment, acalcination temperature of approximately 1200-2000° C. (e.g., 1400° C.in one embodiment) and a calcination time of approximately 2-5 hours(e.g., 3 hours in one embodiment) is used. The spray dried granularparticle size for the mixed powder may have a size distribution ofapproximately 30 μm in one embodiment.

At block 510, optimal plasma spray parameters for plasma spraying aceramic coating using an LPPS or APPS process are selected. Theparameters may be adjusted to values falling within the ranges shown inTable 3 based on a subsequent plasma spray process to be performed. Inone embodiment, optimizing plasma spray parameters includes, but is notlimited to, setting a plasma gun power, chamber pressure and acomposition of spray carrier gas. Optimizing the powder characteristicsand the plasma spray parameters may lead to a coating with a decreasedporosity and an increased density and an increased percentage of fullymelted nodules. Such a decreased porosity and increased density improvesprotection of a coated article from corrosive elements such as plasmas.Also, fully melted nodules are less likely to break free of the ceramiccoating and contaminate the wafer causing particle problems. In oneembodiment, an optimal powder type and an optimal powder sizedistribution are selected for the powder.

At block 512, the article is coated according to the selected powdercharacteristics and plasma spray parameters to form a first plasmaresistant layer. LPPS and APPS processes may melt materials (e.g.,ceramic powders) and spray the melted materials onto the article usingthe selected parameters. The first plasma resistant layer may have athickness of about 20-500 microns, and a thickness of about 100-200microns in a particular embodiment. Additionally, the first plasmaresistant layer may have a porosity of 1-5%. In some instances, thefirst plasma resistant layer has a porosity of around 3-5%.

The plasma spray process may be performed in multiple spray passes. Foreach pass, the angle of a plasma spray nozzle may change to maintain arelative angle to a surface that is being sprayed. For example, theplasma spray nozzle may be rotated to maintain an angle of approximately45 degrees to approximately 90 degrees with the surface of the articlebeing sprayed. Each pass may deposit a thickness of up to approximately25 μm, depending on the plasma spray process that is being performed andthe input parameters. The first plasma resistant layer may have asurface roughness of about 100-300 micro-inches.

At block 514, a PSTF, PSCVD or PSPVD process is selected for forming asecond plasma resistant layer. At block 516, a determination may be madeas to whether the first plasma resistant layer was formed using LPPS orAPPS. If APPS was used for the first plasma resistant layer, then theprocess continues to block 518, and the article is loaded into a vacuumchamber of an LPPS system. Otherwise the process proceeds to block 520,and the PSTF, PSCVD or PSPVD process may be performed following the LPPSprocess.

At block 520, the plasma spray parameters are adjusted or selectedand/or the powder parameters are adjusted or selected to optimizedeposition using the PSTF, PSCVD or PSPVD process. For example, if PSTFis to be performed, the pressure may be reduced to approximately0.1-50.0 Mbar. If PSPVD is to be performed, the pressure may be reducedto approximately 0.1-50.0 Mbar, and the plasma power may be unchanged orincreased. If PSCVD is to be performed, a liquid or vapor is supplied,pressure may be reduced to less than about 0.4 Mbar, and plasma power isreduced to less than about 10 kW. The parameters may be adjusted tovalues falling within the ranges shown in Table 3 based on a subsequentplasma spray process to be performed. For example, if an additionalplasma resistant layer is to be deposited using PSTF, then the plasmaspray parameters would be adjusted to within the ranges shown for PSTF.

At block 522, the article is plasma sprayed using a PSTF, PSPVD or PSCVDprocess to form a second plasma resistant layer. PSCVD, PSPVD and/orPSTF processes may melt or vaporize materials (e.g., ceramic powders, orliquid or gaseous precursors) and spray the melted or vaporizedmaterials onto the article using the selected parameters. The secondplasma resistant layer may have a thickness of less than about 100microns. In one embodiment, the second plasma resistant layer has athickness of approximately 10 microns or less. The second plasmaresistant layer may be conformal, uniform, and denser than the firstplasma resistant layer. In one embodiment, the second plasma resistantlayer has a porosity of less than 1%.

At block 524, it is determined whether to deposit any additional layersfor the plasma resistant ceramic coating. If an additional layer is tobe deposited, the process may return to block 514 for plasma sprayinganother layer using a PSCVD, PSPVD or PSTF process. Alternatively, theprocess may return to block 502, 506 or 508 for plasma spraying anotherlayer using an APPS or LPPS process. Otherwise the method ends.

TABLE 1 Plasma Spray Input Parameters Input LPPS PSPVD PSTF APPS PSCVDParameter Unit Range Range Range Range Range Power of kW  9-300  9-300 9-300  9-300 <100 Plasma Gun Current A 300- 300- 300- 300- <1000 10001000 1000 1000 Gun Voltage V 30-300 30-300 30-300 30-300 <100 PowderFeed g/min.  5-200  5-200  5-200  5-200 5-200 Distance mm 500- 500- 500-50-200 500- 3000 3000 3000 3000 Gas Flow L/min. 30-500 30-500 30-50030-500 30-500 Rate Pressure Mbar 10-100 0.1-50   0.1-50   1013 0.1-50  

Table 1 illustrates input parameters that may be used for coating thearticle using an LPPS process, a PSPVD process, a PSTF process, an APPSprocess, or a PSCVD process. The parameters include, but are not limitedto, power of plasma, gun current, gun voltage, powder feed rate, gunstand-off distance, gas flow rate and chamber pressure.

FIGS. 6-7 illustrate cross sectional side views of articles (e.g.,chamber components) covered by plasma resistant ceramic coatingsincluding two or more protective layers. Referring to FIG. 6, a body 605of the article 600 includes a plasma resistant ceramic coating 606having a first thick film protective layer 608 and a second thin filmprotective layer 610. In one embodiment, the first thick film protectivelayer 608 is a plasma-sprayed layer having a thickness of about 20-500μm and a porosity of about 1-5%. In one embodiment, the thin filmprotective layer is a plasma-sprayed layer having a thickness of about1-100 μm and a porosity of less than 1%. In one embodiment, the thickfilm protective layer is deposited by LPPS and the thin film protectivelayer is deposited by PSTF, PSCVD or PSPVD. In one embodiment, the thickfilm protective layer is deposited by APPS, and the thin film protectivelayer is deposited by one of PSTF, PSPVD or PSCVD.

Examples of ceramics that may be used to form the first thick filmprotective layer 608 and thin film protective layer 610 includeY₃Al₅O₁₂, Y₄Al₂O₉, Er₂O₃, Gd₂O₃, Er₃Al₅O₁₂, Gd₃Al₅O₁₂, a ceramiccompound comprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂ (Y₂O₃—ZrO₂solid solution), or any of the other ceramic materials previouslyidentified. Other Er based and/or Gd based plasma resistant rare earthoxides may also be used to form the thick film protective layer 608 andthin film protective layer 610. In one embodiment, the same ceramicmaterial is not used for two adjacent thin film protective layers.However, in another embodiment adjacent layers may be composed of thesame ceramic.

FIG. 7 illustrates a cross sectional side view of another embodiment ofan article 700 having a plasma resistant ceramic coating 706 thatincludes a stack of protective layers deposited over a body 705 of thearticle 700. Article 700 is similar to article 700, except that plasmaresistant ceramic coating 706 has four protective layers 708, 710, 715,718. As shown, the protective layers may be alternating thick filmprotective layers and thin film protective layers. Alternatively,multiple thick film protective layers may be deposited followed by afinal thin film protective layer. Thick film protective layers may bedeposited by LPPS or APPS and have a thickness of 20-500 microns. Thinfilm protective layers may be deposited by PSTF, PSPVD or PSCVD and havea thickness of 1-100 microns. The plasma resistant ceramic coating 706may have any number of protective layers.

In one embodiment, the bottom protective layers 608, 708 include acoloring agent that will cause the deposited protective layer to have aparticular color. Examples of coloring agents that may be used includeNd₂O₃, Sm₂O₃ and Er₂O₃. Other coloring agents may also be used.Accordingly, when the second protective layer 610, 710 wears away, anoperator may have a visual queue that it is time to refurbish orexchange the article 600, 700.

The preceding description sets forth numerous specific details such asexamples of specific systems, components, methods, and so forth, inorder to provide a good understanding of several embodiments of thepresent disclosure. It will be apparent to one skilled in the art,however, that at least some embodiments of the present disclosure may bepracticed without these specific details. In other instances, well-knowncomponents or methods are not described in detail or are presented insimple block diagram format in order to avoid unnecessarily obscuringthe present disclosure. Thus, the specific details set forth are merelyexemplary. Particular implementations may vary from these exemplarydetails and still be contemplated to be within the scope of the presentdisclosure.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment. Thus, the appearances of the phrase “in oneembodiment” or “in an embodiment” in various places throughout thisspecification are not necessarily all referring to the same embodiment.In addition, the term “or” is intended to mean an inclusive “or” ratherthan an exclusive “or.”

Although the operations of the methods herein are shown and described ina particular order, the order of the operations of each method may bealtered so that certain operations may be performed in an inverse orderor so that certain operation may be performed, at least in part,concurrently with other operations. In another embodiment, instructionsor sub-operations of distinct operations may be in an intermittentand/or alternating manner.

It is to be understood that the above description is intended to beillustrative, and not restrictive. Many other embodiments will beapparent to those of skill in the art upon reading and understanding theabove description. The scope of the disclosure should, therefore, bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled.

What is claimed is:
 1. A method comprising: providing an article;feeding a liquid precursor solution into a plasma spray depositionsystem; and generating, with the plasma spray deposition system, astream directed toward the article, wherein the stream forms a ceramiccoating on the article upon contact therewith, and wherein the ceramiccoating comprises Y₂O₃ and one or more of ZrO₂, Al₂O₃, Er₂O₃, Gd₂O₃,SiO₂, or YF₃.
 2. The method of claim 1, wherein a composition of theceramic coating is selected from: 50-75 mol % of Y₂O₃, 10-30 mol % ofZrO₂, and 10-30 mol % of Al₂O₃; 40-100 mol % of Y₂O₃, 0-60 mol % ofZrO₂, and 0-10 mol % of Al₂O₃; 40-60 mol % of Y₂O₃, 30-50 mol % of ZrO₂,and 10-20 mol % of Al₂O₃; 40-50 mol % of Y₂O₃, 20-40 mol % of ZrO₂, and20-40 mol % of Al₂O₃; 70-90 mol % of Y₂O₃, 0-20 mol % of ZrO₂, and 10-20mol % of Al₂O₃; 60-80 mol % of Y₂O₃, 0-10 mol % of ZrO₂, and 20-40 mol %of Al₂O₃; or 40-60 mol % of Y₂O₃, 0-20 mol % of ZrO₂, and 30-40 mol % ofAl₂O₃.
 3. The method of claim 1, wherein the ceramic coating comprisesZrO₂, Er₂O₃, Gd₂O₃, and SiO₂.
 4. The method of claim 1, wherein theceramic coating comprises 40-45 mol % of Y₂O₃, 0-10 mol % of ZrO₂, 35-40mol % of Er₂O₃, 5-10 mol % of Gd₂O₃, and 5-15 mole % of SiO₂.
 5. Themethod of claim 1, wherein the ceramic coating comprises YF₃.
 6. Themethod of claim 1, wherein a thickness of the ceramic coating is fromabout 20 micrometers to about 500 micrometers.
 7. The method of claim 1,wherein a surface roughness of the ceramic coating is from about 100micro-inches to about 300 micro-inches.
 8. The method of claim 1,wherein a porosity of the ceramic coating is less than about 1%.
 9. Themethod of claim 1, wherein the article is a chamber component selectedfrom a group consisting of a substrate support assembly, anelectrostatic chuck, a ring, a chamber wall, a base, a gas distributionplate, a showerhead, a liner, a liner kit, a shield, a plasma screen, aflow equalizer, a cooling base, a chamber viewport, a chamber lid, anozzle, or a process kit ring.
 10. A method comprising: providing anarticle; feeding a liquid precursor solution into a plasma spraydeposition system; and generating, with the plasma spray depositionsystem, a stream directed toward the article, wherein the stream forms aceramic coating on the article upon contact therewith, and wherein theceramic coating comprises one or more of Y₃Al₅O₁₂, Y₄Al₂O₉, Er₃Al₅O₁₂,Gd₃Al₅O₁₂, Nd₂O₃, or a ceramic compound comprising Y₄Al₂O₉ and asolid-solution of Y₂O₃—ZrO₂.
 11. A method comprising: providing anarticle, the article comprising a ceramic coating disposed thereon;feeding a liquid precursor solution into a plasma spray depositionsystem; and generating, with the plasma spray deposition system, astream directed toward the article, wherein the stream forms a secondceramic coating on the first ceramic coating upon contact therewith, andwherein at least one of the first or second ceramic coatings comprisesY₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂.
 12. The method of claim 11,wherein at least one of the first or second ceramic coatings comprises acomposition selected from: 50-75 mol % of Y₂O₃, 10-30 mol % of ZrO₂, and10-30 mol % of Al₂O₃; 40-100 mol % of Y₂O₃, 0-60 mol % of ZrO₂, and 0-10mol % of Al₂O₃; 40-60 mol % of Y₂O₃, 30-50 mol % of ZrO₂, and 10-20 mol% of Al₂O₃; 40-50 mol % of Y₂O₃, 20-40 mol % of ZrO₂, and 20-40 mol % ofAl₂O₃; 70-90 mol % of Y₂O₃, 0-20 mol % of ZrO₂, and 10-20 mol % ofAl₂O₃; 60-80 mol % of Y₂O₃, 0-10 mol % of ZrO₂, and 20-40 mol % ofAl₂O₃; or 40-60 mol % of Y₂O₃, 0-20 mol % of ZrO₂, and 30-40 mol % ofAl₂O₃.
 13. The method of claim 11, wherein at least one of the first orsecond ceramic coatings comprises Y₂O₃ and one or more of ZrO₂, Er₂O₃,Gd₂O₃, or SiO₂.
 14. The method of claim 11, wherein at least one of thefirst or second ceramic coatings comprises 40-45 mol % of Y₂O₃, 0-10 mol% of ZrO₂, 35-40 mol % of Er₂O₃, 5-10 mol % of Gd₂O₃, and 5-15 mole % ofSiO₂.
 15. The method of claim 11, wherein at least one of the first orsecond ceramic coatings comprises one or more of Y₃Al₅O₁₂, Y₄Al₂O₉,Er₃Al₅O₁₂, Gd₃Al₅O₁₂, Nd₂O₃, or a ceramic compound comprising Y₄Al₂O₉and a solid-solution of Y₂O₃—ZrO₂.
 16. The method of claim 11, whereinat least one of the first or second ceramic coatings ceramic coatingcomprises Y₂O₃ and YF₃.
 17. The method of claim 11, wherein at least oneof the first or second ceramic coatings has a thickness from about 20micrometers to about 500 micrometers.
 18. The method of claim 11,wherein the second ceramic coating has a surface roughness of theceramic coating is from about 100 micro-inches to about 300micro-inches.
 19. The method of claim 11, wherein at least one of thefirst or second ceramic coatings has a porosity of the ceramic coatingis less than about 1%.
 20. The method of claim 11, wherein the articleis a chamber component selected from a group consisting of a substratesupport assembly, an electrostatic chuck, a ring, a chamber wall, abase, a gas distribution plate, a showerhead, a liner, a liner kit, ashield, a plasma screen, a flow equalizer, a cooling base, a chamberviewport, a chamber lid, a nozzle, or a process kit ring.